Conventionally, there exists a washer pump system mounted on the automobile, and selectively supplying a washer fluid inside a washer tank to either a front window or a rear window.
As this kind of washer pump system, for example, there is known, for example, a washer pump system comprising a pump device including two discharge openings discharging the washer fluid with a discharge pressure in which a magnitude relation reverses according to a rotational direction of an impeller; and a valve mechanism including two derivation flow channels respectively communicated with each discharge opening, and operating by a pressure difference of the discharge pressure so as to close the derivation flow channel having a lower pressure, and also to open the derivation flow channel having a higher pressure among the two derivation flow channels (for example, see Patent Document 1).